Total hip replacement (THR) is a highly effective, frequently performed and costly surgery. While purchases of care seek centers of excellence for THR, at present there are no validated measures of the quality of THR. Further, it is not clear whether easily accessible administrative data provide adequate information to rate THR quality, or whether more expensive data sources such as chart review and patient interview are necessary. The aim of this study is to validate indicators of the quality of elective primary and revision total hip replacement. The proposal takes advantage of a study already funded by NIH which examines the association between hospital and surgeon procedure volume and the outcomes of THR. The parent study analyzes Medicare claims of over 100,000 patients undergoing THR in 1995. Also, on a random 2000 of these subjects, we 1) review medical records to ascertain case severity, process of care and complications; 2) interview patients to assess satisfaction and functional status; and 3) survey hospitals to evaluate structural aspects of the setting in which surgery was done. An indicator of quality is valid if it is associated with the principal outcomes of THR--mortality, complications, and functional status only. Thus, we propose in this application to examine associations between process and structural indicators and these principal outcomes of THR in our rich dataset, adjusting for measures of case severity. We will also create and validate a cumulative index of the quality of THR which THR aggregates individual indicators identified both with statistical analyses of our data along with recommendations of an expert panel. We will assess the marginal benefit of using various sources of data for assessing quality of THR. Thus, this study will delineate the optimal data sources and data elements for measuring and ultimately improving the quality of THR.